1. Field of the Invention
The present invention relates to pharmaceutical compositions, and more particularly to pharmaceutical compositions for oral administration of a medicament, which contain an effervescent agent for enhancing oral drug absorption across the buccal, sublingual, and gingival mucosa.
2. Description of Prior Art
Effervescents have been shown to be useful and advantageous for oral administration. See Pharmaceutical DosageForms: Tablets Volume I, Second Edition. A. Lieberman. ed. 1989, Marcel Dekker, Inc. As discussed in this text, and as commonly employed, an effervescent tablet is dissolved in water to provide a carbonated or sparkling liquid drink. See also U.S. Pat. Nos. 5,102,665 and 5,468,504 to Schaeffer, herein incorporated by reference. In such a drink, the effervescent helps to mask the taste of medicaments.
Effervescent compositions have also been employed for use as taste masking agents in dosage forms which are not dissolved in water prior to administration. For example, U.S. Pat. No. 4,639,368 describes a chewing gum containing a medicament capable of absorption through the buccal cavity and containing a taste masking amount of an effervescent.
More recently effervescents have been employed to obtain rapid dissolution and/or dispersion of the medicament in the oral cavity. See U.S. Pat. Nos. 5,178,878 and 5,223,264. The effervescent tends to stimulate saliva production thereby providing additional water to aid in further effervescent action. These dosage forms give an agreeable presentation of the drug, particularly for patients who have difficulty in swallowing tablets or capsules. PCT application WO 97/06786 describes pre-gastric absorption of certain drugs using rapidly-disbursing dosage forms.
Various proposals have been advanced for oral mucosal administration of various drugs. When drugs are absorbed from the oral mucosa, they bypass the gastrointestinal and hepatic metabolism process. This can lead to a faster onset of action and/or improved bioavailability of a drug. However, many compounds do not rapidly penetrate the oral mucosa. See, e.g., Christina Graffner, Clinical Experience with Novel Buccal and Sublingual Administration; NOVEL DRUG DELIVERY AND ITS THERAPEUTIC APPLICATION, edited by L. F. Prescott and W. S. Nimmo (1989); David Harris & Joseph R. Robinson, Drug Delivery via the Mucous Membranes of the Oral Cavity; JOURNAL OF PHARMACEUTICAL SCIENCES, Vol. 81 (January 1992); Oral Mucosal Delivery, edited by M. J. Rathbone, which are herein incorporated by reference. The compounds which may be well absorbed per-orally (through the gastrointestinal tract) may not be well absorbed through the mucosa of the mouth because the oral mucosa is less permeable than the intestinal mucosa and it does not offer as big a surface area as the small intestine.
Despite these and other efforts toward increasing the permeation of medicaments across the oral mucosa, there have been unmet needs for improved methods of administrating medicaments across the oral mucosa.